Methods of making a color filter for a liquid crystal display panel or the like include dyeing, pigment dispersion, printing, and electrodeposition methods. Of these fabrication methods, the printing method has a drawback with respect to accuracy, and the electrodeposition method has a drawback concerning patterning restrictions, and for those reasons the dyeing method and pigment dispersion method have been most widely used in the art.
However, the dyeing method and the pigment dispersion method each require a lithography step for forming the pixel regions for each of the first color, second colors and third color, which is a big obstacle to improving the efficiency of mass producing the color filter. One method for forming pixels without such a lithography step for each color is an inkjet method of making a color filter, which is disclosed in a number of publications, such as Japanese Patent Application Laid-Open No. 59-75205 and Japanese Patent Application Laid-Open No. 61-245106. Using an inkjet method to form the color pattern improves the efficiency of use of materials and shortens the process, and it is also possible to control the formation of the color pattern and thus obtain a color filter that is inexpensive but of a high quality.
In such a method of making a color filter using an inkjet method, one means that has been proposed to prevent ink from spreading outside of each colored region, and thus implement highly precise coloring, is to use pixel delimiting regions that are formed previously by photolithography on the substrate. Ink filling concavities are thus formed on the substrate by the pixel delimiting regions, to control the shape of a color pattern that is formed by filling these ink filling concavities with ink.
These pixel delimiting regions are often formed of an opaque material so that they also function as a black matrix (hereinafter abbreviated to BM).
In this case, a high level of precision is required for the formation of the pixel delimiting regions, but it is difficult to perform such highly precise processing while improving the mass-productivity of the process. In addition, flatness is required when forming a transparent electrode on the color filter, but it has been difficult to increase the precision of this flatness in the past.
The present invention has been devised in order to solve the above problems, and has the objective of providing a method of making an inexpensive, highly precise color filter with a reduced number of steps, as well as a color filter fabricated by that method.